I am Mission Leader in my Ward. I know that individual members can verify their own locations in LDSmaps,but only Ward leadership, IE Bishopric and Clerks can verify all members locations. Can this be extended also to WMLs? Since the missionaries can help verify locations, it seems that it would be a good way to verify locations.

Not likely, as only membership clerks are the ones authorized to edit membership records. While missionaries surely help in the task of locating/verifying locations, the responsibility for editing the record lies with the clerks which, in the developer's view, apparently includes verifying locations on the map. As mentioned, if your ward wants to have you serve in that capacity, they just need to call you as a membership clerk as well, or at least list you as one in MLS.